For the complete documentation index, see llms.txt.

Autumnal Equinox Day API

datetime 1 credit / call v2026-04-22

Return autumn equinox date, UTC time, seasonal markers, and optional countdown data.

One POST adds Autumnal Equinox Day to your app, site, workflow, or agent — formula, validation, edge cases, and docs already handled.

prefer a UI? open Autumnal Equinox Day on miniwebtool.com →

Start free — get a key → 1,000 credits · no card · 30 seconds

Endpoint

POST · 1cr
POST https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run

Request body

Field Type Req.
year int
hemisphere
north | south
str
as_of_utc
Optional ISO datetime for countdown
str | None

Cost & access

  • 1 credit per successful call — failed calls refund.
  • Starts on: Free.
  • Max payload: 65536 bytes.
  • Privacy mode: hash_only
  • Available on: free, starter, pro, business, scale

Response envelope

{
  "request_id": "01K...",
  "tool": "autumnal-equinox-day",
  "tool_version": "2026-04-22",
  "credits_used": 1,
  "result": { ... }
}

Try it

Stored only in this browser tab. Playground test key is prefilled and only works on this page. Get a live key →
north | south
Optional ISO datetime for countdown

Code examples

curl -X POST https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run \
  -H 'Authorization: Bearer mwt_live_YOUR_KEY' \
  -H 'Content-Type: application/json' \
  -d '{}'
import requests

resp = requests.post(
    'https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run',
    headers={'Authorization': 'Bearer mwt_live_YOUR_KEY'},
    json={},
)
resp.raise_for_status()
print(resp.json())
const resp = await fetch(
  'https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run',
  {
    method: 'POST',
    headers: {
      'Authorization': 'Bearer mwt_live_YOUR_KEY',
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({}),
  }
);
const data = await resp.json();
console.log(data);
<?php
$ch = curl_init('https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run');
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer mwt_live_YOUR_KEY',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => json_encode([

]),
]);
$resp = curl_exec($ch);
curl_close($ch);
print_r(json_decode($resp, true));
require 'net/http'
require 'json'
require 'uri'

uri = URI('https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = (uri.scheme == 'https')

req = Net::HTTP::Post.new(uri)
req['Authorization'] = 'Bearer mwt_live_YOUR_KEY'
req['Content-Type'] = 'application/json'
req.body = {

}.to_json

resp = http.request(req)
puts JSON.parse(resp.body).inspect
package main

import (
  "bytes"
  "encoding/json"
  "fmt"
  "io"
  "net/http"
)

func main() {
  body, _ := json.Marshal(map[string]interface{}{
,
  })
  req, _ := http.NewRequest("POST", "https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run", bytes.NewReader(body))
  req.Header.Set("Authorization", "Bearer mwt_live_YOUR_KEY")
  req.Header.Set("Content-Type", "application/json")

  resp, err := http.DefaultClient.Do(req)
  if err != nil { panic(err) }
  defer resp.Body.Close()
  out, _ := io.ReadAll(resp.Body)
  fmt.Println(string(out))
}
import java.net.URI;
import java.net.http.*;

var client = HttpClient.newHttpClient();
var req = HttpRequest.newBuilder()
    .uri(URI.create("https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run"))
    .header("Authorization", "Bearer mwt_live_YOUR_KEY")
    .header("Content-Type", "application/json")
    .POST(HttpRequest.BodyPublishers.ofString("{}"))
    .build();

var resp = client.send(req, HttpResponse.BodyHandlers.ofString());
System.out.println(resp.body());
how-to call autumnal-equinox-day
  1. Get an API key
    Get an API key. Sign up free for a bearer token. 1,000 credits/month, no card.
  2. Assemble the JSON body
    Required fields: . See the Request body table above for the full schema.
  3. POST to https://api.miniwebtool.com/v1/tools/autumnal-equinox-day/run
    Headers: Authorization: Bearer <key> and Content-Type: application/json. Copy-paste snippets in 7 languages are under Code examples.
  4. Parse the response
    Envelope: {request_id, tool, tool_version, credits_used, result}. The typed output lives in result.
faq frequently asked
What does the Autumnal Equinox Day API do?+

Return autumn equinox date, UTC time, seasonal markers, and optional countdown data. Use it to add this utility without rebuilding formulas, validation, examples, and documentation.

How much does one call to Autumnal Equinox Day cost?+

1 credit per successful call. Failed calls (validation errors, 5xx) don't bill.

What parameters does the Autumnal Equinox Day API require?+

Required fields: (none). Full schema at /v1/openapi.json.

Is the Autumnal Equinox Day API deterministic?+

Yes — same input, same output, forever. Tool version 2026-04-22; output shape is stable within a major version.

Can an AI agent call the Autumnal Equinox Day API?+

Yes. Connect to https://api.miniwebtool.com/v1/mcp over the Model Context Protocol. The agent discovers `autumnal-equinox-day` with its JSON Schema automatically, so the model can plan while MiniWebtool handles the exact tool result.

What format does the API return?+

JSON with a stable envelope: `{request_id, tool, tool_version, credits_used, result}`. Errors are RFC 7807 `application/problem+json`.

mcp use from an AI agent

Every endpoint on this site is also exposed via the Model Context Protocol at https://api.miniwebtool.com/v1/mcp. Claude, Cursor, and any MCP-capable agent can discover this tool (autumnal-equinox-day) and its JSON Schema automatically — no client codegen.

# List tools the agent can call
curl -s https://api.miniwebtool.com/v1/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' \
 | jq '.result.tools[] | select(.name=="autumnal-equinox-day")'
see-also related datetime tools